Internal-combustion engine



Aug. 14, 1945. F, wElNREB INTERNAL-COMBUSTION ENGINE Filed Jan. 24, 1944 Patented ug. 14, 1945 Falk Weinreb, London, England Application January 24, 1944, Serial N0."519,511

In Great Britain January 27, v1943 s claims. icl. 12a-vs) This invention relates to internal combustion engines of the kind having a main piston working in a cylinder and an auxiliary piston which works in an extension of the cylinder, which extension-.may either be axially in line with the cylinder or inclined at an angle thereto.

Hitherto, it has been proposed to operate engines of this kind in such a manner that maximum compression and ignition occur not as usual ,when the piston is in the dead center position and the torque factor is zero, but when thepiston has moved away from the dead center, and the torque factor has attained a substantial value. To obtain this result the main compression was eiected as usual by the main piston on its travel towards the dead center and the compression was maintained as the main piston moved away from the dead center by moving the auxiliary piston in the same direction until at a crank angle of about 30 ignition was effected; or an extra degree of compression was obtained by moving the auxiliary piston more rapidly towards the main piston until ignition was effected.

'According to the present invention, only part of the compression sumcient to cushion the reciprocating parts is eiected by the working piston on its travel towards the dead center and the main compression is eiected as the main piston moves away from the dead center byl the auxiliary piston moving more rapidly towards the main piston, ignition taking place when the torque factor has attained a substantial value,

for example, at a crank angle of about 35, whereupon the movement of the auxiliary piston towards the main piston is continued so that combustion takes place at decreasing volume.

It will be realized that the work done by the main piston in compressing the charge on its travel to the dead center is entirely negative, but the work of compression by the auxiliary piston takes place when the main piston is on its return stroke and therefore the auxiliary piston in compressing the charge is doing positive work on the main piston. Consequently, by effecting the main compression by means of the auxiliary piston, the advantage is obtained that the negative work done by the main piston in compressing the charge is reduced to a minimum and the eiliciency of the engine is increased. Also, by continuing the movement of the auxiliary piston towards the main piston after ignition has occurred a more rapid rise in pressure is obtained, which again has a benecial effect on the eiliciency.

In accordance with a further feature of the invention, a further supply oi fuel may be injected into the cylinder and the exploded or lburning charge simultaneously further compressed in order to develop additional power for the purpose of meetingoverloads.

4The accompanying drawing shows diagrammatically in vertical section a four-cycle internal combustion engine constructed in accordance with one of various possible embodiments fof the invention.

Referring to the drawing, the number I represents the cylinder of the internal combustion engine, 2 the main piston rod and 3 the connecting rod. In place of the usual cylinder head, the

cylinder I is provided with an extension 4 in which an auxiliary piston 5 is movable in the axial direction. The auxiliary piston 5 is operated by a: lever 6 which is pivoted at 'I intermediate its ends and of which one end is provided with a slot 8 which is in engagement with a pin 9 fixed to a rod I0 connected to the .auxiliary piston 5. The other end of the lever 6 is pivotally connected by means of a pin II to one end of a rod I2. The opposite end of the rod I2 is pivotally connected by means of a link I3 to a pivot Il mounted on the cylinder extension 4 and carries a-roller I5 which is operated by a cam I6 driven from the crankshaft against the action of a compression spring I1 which is arranged between the link I3 and an abutment IB ilxed on the cylinder extension 4. I'he cylinder is provided as usual with inlet and exhaust valves of which only the inlet valve I9 is visible in the drawing.

The method of operation is as follows: Assuming that the main piston has just completed its compression stroke and is at the innerdead center position M-M, the auxiliary piston 5 is then in the position A-A in which it is separated from the main piston by such a distance as to allow the compression of the combustible mixture sulcient to cushion the reciprocating parts, but insuilicient to cause ignition, which does not take place at this stage. When the main piston begins to make its return stroke, the auxiliary piston 5 is moved more quickly in the same direction, owing to the part af--b of the cam I5 bearing against the roller I5, so that the main compression takes place, and maximum compression is reached when the main piston has traversed a part of its stroke, for example at a crank angle of about 35, whereupon ignition takes place. The main piston and auxiliary piston are then in the position indicated in full lines in the drawing, and the point b of the cam I6 bears against the roller` I5. As the main piston proceeds to make the expansion stroke, the auxiliary piston follows the main piston more rapidly, owing to the roller I riding onto the part b-c of the cam I6, and then remains stationary. During the following exhaust stroke of the main piston, as the main piston returns to the inner dead center position, the roller I5 rides on to the part d-e of the cam, and the auxiliary piston is thereby moved to a position Ai-A1 in which it is clear of the main piston 2 when the latter again reaches the inner dead center position M-M. The suction stroke of the main piston 2 then takes place in the usual manner and the auxiliary piston is moved back to the position Az-Az, owing to the roller I5 riding on to the surface f-g of the cam I6, and remains in this position while the suction stroke is completed. During the following compression stroke of the main piston, the roller I5 rides on to the part hf-a of the cam I6 whereby the auxiliary piston is moved towards the main piston until it reaches its original position A-A, whereupon the cycle of operations is repeated as before. The positions A--A and Az-Az may vary according to the volume of the mixture or air drawn in.

Additional fuel may be injected into the cylinder during the expansion stroke and while the movement of the auxiliary piston is continuing, so that the already burning charge is compressed to a higher pressure and the additional fuel is simultaneously ignited and a further rise in pressure occurs. Similarly additional fuel may also be injected when vthe movement of the auxiliary piston is not continued towards the main piston after ignition has taken place.

For the purpose of dealing with overloacls, the movement of the auxiliary piston during the expansion stroke may be continued in the same direction after ignition has taken place, for which purpose the cam I6 may be provided with an additional cam surface I1, which is indicated by a dotted line in the drawing, whereby the pressure may be kept constant during any desired portion of the stroke. Again additional fuel may be injected into the cylinder during the expansion stroke and while the movement of the aux-1 iliary piston is continuing, so that the already burning` charge is compressed to a higher pressure and `the additional fuel is simultaneously ignited and a further rise inpressure occurs. Similarly additional fuel may also be injected when the movement of the auxiliary piston is not continued in the same direction after ignition has taken place.

As shown in the drawing, the auxiliary piston i f working conditions the cam I6 may be movable axially on its shaftand its operative surface may be of considerable width, its contour differing at, different points in its width, so

that by shifting the cam along its shaft a cam surface of different contour acts on the roller I5. In this way, for example, maximum compression may be caused to take place at any desired crank angle and reversing of the engine may be effected.

The arrangement described may be adapted with slight alterations, for example as regards timing, for two-stroke Acycle engines.

The invention is applicable to petrol, oil and gas engines both of the compression ignition type and also to engines in which ignition is effected by means of an ignition device.

'I'he invention, in addition to possessing the advantage that a. higher maximum and also a higher mean tangential pressure is obtained as compared with a normal engine, has the further advantage that, in the case of engines, working with aspirated mixtures of air and gas or air and gasified fuel, a higher compression ratio can be used because there is no danger of preignition since the piston has already begun to make its expansion stroke when ignition occurs. Also, by suitably operating the auxiliary piston, it is possible to cause ignition to take place at any desired point during the stroke of the main piston.

The positions A--A and Az-Az may vary according to the volume of mixture or air drawn in.

The port 23 may be fitted with a valve through which air may be drawn in or forced in.

I claim:

1. An internal combustion engine having a cylinder, a main piston which is reciprocated in the cylinder, a chamber communicating with the main cylinder, an auxiliary piston movable in said chamber, means whereby -said auxiliary piston is moved in such a manner that maximum compression takes place after the main piston has moved away from the dead centre position and the torque factor has attained a substantial value, ignition taking place when the compression pressure is substantially a maximum, and means whereby the auxiliary piston is moved in the same direction as the main piston after ignition has occurred, so that the pressure in the cylinder is maintained at a desired value during a predetermined part of the expansion stroke of the main piston. v

2. An internal combustion engine having a cylinder, piston working in the cylinder, means whereby the maximum pressure period effected by the ignition is caused to take place in the vcylinder when the torque factor has attained a substantial value and means whereby additional fuel is injected into the cylinder during the expansion stroke of the main piston.

. 3. An internal combustion engine having a cylinder, a main piston which is reciprocated in the cylinder, a chamber communicating with the main cylinder, an auxiliary piston movable in said chamber, 'means whereby said auxiliary piston is moved in such a manner that maximum compression takes place after the main piston has moved away from the dead centre position and the torque factor has attained a value of at least 0.5, ignition being effected when the compression pressure is substantially a maximum, and means whereby the auxiliary piston is moved in the same direction as the main piston after ignition has occurred, so that the pressure in the cylinder is maintainedv at a desiredvalue during a predetermined part of the expansion stroke of the main piston.

4. An internal combustion engine having a cylinder and a piston' working in the cylinder, and means whereby maximum compression and ignition of the charge are caused to take place in the cylinder after the piston has moved away from the dead centre position, and the torque factor has attained a substantial value, and means whereby additional fuel is injected into the cylinder during the expansion strokeot the main piston.

5. An internal combustion engine having a cylinder and a piston working in the cylinder.

ignition of the charge are caused to take place in the cylinder after the piston has moved away FALK WEINREB.

and means whereby maximum compression and 5 main piston. 

